Liquid crystal composition, and element and device using the same

Abstract

A liquid crystal composition is disclosed having antiferroelectric phases at two temperature ranges. A liquid crystal element and device using the liquid crystal composition are also disclosed.

We claim: 
     
       1. The liquid crystal composition having antiferroelectric phases at two temperature ranges comprising not less than 80 parts by weight of a compound represented by the general formula (III): ##STR20## wherein R 1  is an alkyl group having from 4 to 18 carbon atoms, R 2  is an alkyl group having from 4 to 18 carbon atoms, and * shows an asymmetric carbon atom, and less than 20 parts by weight of a compound represented by the general formula (IV): ##STR21## wherein R 3  and R 4  are independently selected from the group consisting of alkyl groups having from 4 to 18 carbon atoms, and * shows an asymmetric carbon atom, the compounds of formula (III) and formula (IV) having an optical purity of higher than 80% e.e., respectively; when the compound of the general formula (III) is an R-isomer, the compound of the general formula (IV) is also an R-isomer; and when the compound of the general formula (III) is an S-isomer, the compound of the general formula (IV) is also an S-isomer. 
     
     
       2. The liquid crystal compound according to claim 1 wherein the compound is represented by the general formula (I) ##STR22## wherein R 1  and R 2  are independently selected from the group consisting of alkyl groups having from 4 to 18 carbon atoms, and * shows an asymmetric carbon atom and wherein the compound represented by the general formula (I) has an optical purity of higher than 80% e.e. 
     
     
       3. The liquid crystal compound according to claim 2 wherein the compound represented by the general formula (I) is 4(1-methylheptyloxycarbonyl)phenyl 4'-octylbiphenyl-4-carboxylate represented by the formula (II): ##STR23## 
     
     
       4. The liquid crystal composition according to claim 1 wherein the liquid crystal composition is a mixture of not less than 80 parts by weight of R-(-)-4(1-methylheptyloxycarbonyl)phenyl 4'-octylbiphenyl-4-carboxylate and less than 20 parts by weight of R-(-)-4-(1-methylheptyloxycarbonyl)phenyl 4'-octylcarbonyloxybiphenyl-4-carboxylate represented by the formula (V): ##STR24## 
     
     
       5. The liquid crystal composition comprises 80 to 40 parts by weight of a compound represented by the general formula (VII): ##STR25## wherein R 1  and R 2  are independently selected from the group consisting of alkyl groups having from 4 to 18 carbon atoms, and * shows an asymmetric carbon atom, and 20 to 60 parts by weight of a compound represented by the general formula (IV): ##STR26## wherein R 3  and R 4  are independently selected from the group consisting of alkyl groups having from 4 to 18 carbon atoms, and * shows an asymmetric carbon atom, the compounds having an optical purity of higher than 80% e.e., respectively; when the compound of the general formula (VII) is an R-isomer, the compound of the general formula (IV) also being an R-isomer; and when the compound of the general formula (VII) is an S-isomer, the compound of the general formula (IV) also being an S-isomer. 
     
     
       6. The liquid crystal composition according to claim 5 wherein the liquid crystal composition is a mixture of 80 to 40 parts by weight of 4-(1-methylheptyloxycarbonyl)phenyl 4'-octyloxycaroxybiphenyl-4-carboxylate represented by the formula (VIII): ##STR27## and 20 to 60 parts by weight of 4-(1-methyheptyloxycarbonyl)phenyl 4'-octylcarbonyloxybiphenyl-4-carboxylate represented by the formula (IX): ##STR28## 
     
     
       7. A liquid crystal element in which a liquid crystal composition is inserted between a pair of electrode substrates characterized in that the liquid crystal composition has an antiferroelectric phase in two temperature ranges. 
     
     
       8. The liquid crystal element according to claim 7 wherein the liquid crystal composition contains a compound represented by the general formula (I): ##STR29## wherein R 1  and R 2  are independently selected from the group consisting of alkyl groups having from 4 to 18 carbon atoms, and * shows an asymmetric carbon atom, and wherein the compound of the general formula (I) has an optical purity of higher than 80% e.e. 
     
     
       9. The liquid crystal element according to claim 8 wherein the compound of the general formula (I) is 4(1-methylheptyloxycarbonyl)phenyl 4'-octylbiphenyl-4-carboxylate represented by the formula (II): ##STR30##   
     
     
       10. The liquid crystal element according to claim 7 wherein the liquid crystal composition comprises not less than 80 parts by weight of a compound represented by the general formula (III): ##STR31## wherein R 1  is an alkyl group or alkoxy group having from 4 to 18 carbon atoms, R 2  is an alkyl group having from 4 to 18 carbon atoms, and* shows an asymmetric carbon atom, and less than 20 parts by weight of a compound represented by the general formula (IV): ##STR32## wherein R 3  and R 4  are independently selected from the group consisting of alkyl groups having from 4 to 18 carbon atoms, and * shows an asymmetric carbon atom, the compounds of formula (I) and formula (II) having an optical purity of higher than 80% e.e., respectively, when the compound of the general formula (III) is an R-isomer, the compound of the general formula (IV) is also being an R-isomer; and when the compound of the general formula (III) is an S-isomer, the compound of the general formula (IV) is also an S-isomer. 
     
     
       11. The liquid crystal element according to claim 7 wherein the liquid crystal composition is a mixture of not less than 80 parts by weight of R-(-)-4(1-methylheptyloxycarbonyl)phenyl 4'-octylbiphenyl-4-carboxylate having an optical purity of greater than 80% e.e. and less than 20 parts by weight of R-(-)-4-(1-methylheptyloxy-carbonyl)phenyl 4'-octylcarbonyloxybiphenyl-4-carboxylate represented by the formula (V): ##STR33## 
     
     
       12. A liquid crystal device having the crystal element according to any one of claims 7,8,9,10 or 11 in which a temperature compensatory circuit is provided to stably maintain the temperature range in which an antiferroelectric phase of a liquid crystal composition at high temperature side appears. 
     
     
       13. A liquid crystal device having a liquid crystal element according any one of claims 7, 8, 9, 10 or 11, said liquid crystal device having a temperature compensatory circuit to maintain the temperature range in which an antiferroelectric phase of a liquid crystal composition at a high temperature side appears, and wherein said liquid crystal device is driven at a temperature in the temperature range in which an antiferroelectric phase of a liquid crystal composition at a high temperature side appears.